In the packaging of carbonated beverages, it has been common to fill the glass or plastic container and apply a closure such as a threaded closure or crown closure to seal the container.
One type of closure that has been utilized in connection with glass or plastic containers for carbonated beverages is a metal roll-on closure wherein the peripheral skirt of the closure is rolled to deform the skirt into conformity with the threads of the container. It has also been suggested that plastic closures having a top wall and a peripheral skirt with internal threads be utilized. In such plastic closures, the top wall seals with the open end or finish of the container. At low volumes of carbonation on the order of one or two volumes of carbonation, an adequate seal is provided. However, where the contents are at three or four volumes of carbonation, the carbonation pressure builds up against the top wall, deforms the top wall and reduces the effectiveness of the seal. This source of incipient leakage is further complicated by the manufacturing tolerances of the container, especially of the glass container. Attempts have been made to stiffen the top wall or otherwise prevent the deflection at the top wall with the consequent loss of the seal.
In both the metal and plastic containers, it has become necessary to add tamper indicating rings which are attached to the skirt of the closure and are torn or broken from the closure when the closure is removed.
As far as applicant is aware, no plastic closures have been successfully used in carbonated beverages which are of the snap-on type.
Another problem with respect to such constructions is that the high pressure of the contents sometimes causes a sudden surge of the contents out of the container when the closure is removed. It is therefore desirable to provide some type of pressure relief before the closure is removed.
In the packaging of liquids that are not carbonated, one type of container that is commonly used is of the flexible or bag type commonly known as a "bag in the box" type wherein a dispensing closure valve is attached to the bag for dispensing the contents such as milk or wine.
Such containers are utilized with dispensing closure valves, for example, such as shown in U.S. Pat. Nos. 3,400,866, 3,443,728, 3,972,452 and 4,211,348. These dispensing closure valves consist of a stem or spout attached to the container and a plastic snap-on closure which has a transverse wall in the form of a frustoconical peripheral portion and a flat transverse bottom portion. The peripheral portion seals against portions of the stem. When it is desired to dispense the contents, a tab on the flat portion is manipulated to flex the frustoconical wall portion out of engagement with the stem. In U.S. Pat. No. 3,400,866, an annular wall on the transverse wall engages an annular radially inwardly extending bead on the stem to provide the seal. However, internal pressure caused by gravity, dropping the package or by gases within the package will tend to force the seal apart. Similarly, U.S. Pat. No. 3,443,728 provides for a portion of the transverse wall to engage the free edge of the stem to provide the seal. Internal pressure will tend to move the transverse wall away from the sealing area. In U.S. Pat. No. 3,972,452, the transverse wall is formed with an annular sealing surface that engages the internal surface of the stem. However, the internal pressure on the transverse wall will tend to pull the cylindrical surface away from the surface of the stem. In U.S. Pat. No. 4,211,348, the transverse wall is formed with an annular bead that engages the cylindrical surface of the stem. Here again, internal pressure will move the annular bead away from the cylindrical surface.
The dispensing closure valves shown in the aforementioned patents cannot be used on containers where the contents are at high pressure.
Accordingly, among the objectives of the present invention are to provide a carbonated beverage package wherein the contents of the package are effectively maintained without the loss of pressure; wherein the container does not require special forming such as threads; wherein the closure can be applied readily without the formation of threads; wherein the closure and the container are more readily made and therefore lower in cost.
Among the further objectives of the invention are to provide a plastic closure for carbonated beverage containers which is of the snap-on type; which will withstand carbonation at three or four volumes; which utilizes an internal self-locking seal; which accommodates variations in pressure; which incorporates venting for safety purposes; which will withstand top loads; which includes a child and tamper resistant feature; which will accommodate manufacturing tolerances in the container; which is resealable; which is easy to open; which incorporates a double seal; and which utilizes less material and therefore is less expensive then prior closures for carbonated beverages.
In accordance with the invention, the carbonated beverage package comprises a container having an opening with a peripheral lip defining a free edge and a downwardly and outwardly inclined sealing surface spaced from the free edge of said peripheral lip and a closure of plastic material, such that it will flex in thin cross section, having an annular wall, a radial wall engaging the free edge of the peripheral lip of the container, and a transverse wall defining a convex surface facing inwardly of the container. The closure has a downwardly and outwardly inclined integral annular sealing surface at the juncture of the axial wall and transverse wall which engages the sealing surface of said container and places said axial wall under tension. The closure has a pressure relief rib at the juncture of the radial wall and axial wall such that axial force in the area overlying the rib will move a portion of the annular sealing surface of the closure away from the sealing surface of the container so that the pressure of the contents in the container can be relieved through a pressure relief opening through to the atmosphere and the closure can thereafter be readily removed from the container.